Cake-maker, say, drinking one more bitter (5)
I believe the answer is:
icier
'bitter' is the definition.
Both the answer and definition are comparative adjectives. Perhaps you can see a link between them that I don't see?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for icier that I've seen before include "increasingly frigid" , "More chilly" , "with more reserve" , "Even more frozen" , "much less friendly" .)